Refrigerating system



Feb-25; 1941 -I B. DE H. MILLER 2233,@59

* I REFRIGEATING SYSTEM Filed June 21, 193s u v wt ATTORNEYSREFRIGERATING SYSTEM 'Bruce De Haven Miller, tov The Girdler Corpocorporation of Delaware PATENT oi-FicE Louisville, xy.. minor ration,

Louisville, Ky., a

Appiicauon'sime 21,1938, serial No. 214,8154v 1i claims. (ci. isz-12s)This invention relates to that type of refrigerating system in which therefrigerating action results from the vaporization of a volatilerefrigerant liquid and in which the resulting vapors arel withdrawn,compressed, condensed and re-l turned for'revaporization.

In such systems it has been found that despite theuse of oil traps andimproved packing means for the compressor, a certain amount of lubrileating oil .used in the compressor ordinarily will nd its way into therefrigerating system.` Such oil being substantially non-volatile at there-l frigerating temperature will,v after a period of time, form filmsupon the heat transfer surface and in the piping and valves of theentire system. Such deposits on the heat transfer surface. have aninsulating effect which often materially reduces the eiiiciency of theheat'transfer.

Where the evaporating liquid gasies in direct contact with the heatexchange surface, the bubbles of gas often adhere to the surface or intraveling along the surface tend to space the volatile liquid fromcontact with portions of the heat transfer surface, and thereby tend toreduce the efficiency of the refrigerant liquid.

One object of the present invention is to pro- 'vide an improved methodin which the formation of insulating lrns of lubricating oil on the heattransfer surface is prevented. or in case such films be formed, theywill be diluted ,and constantly and effectively removed from saidsurface whereby an improved heat transfer is obtained.

V an improved process in which gaseous films and bubbles generated bythe vaporization of the volatile refrigerant are removed fromorprevented from forming on the heat `transfer surface.

A further object is to provide a method where? bythe heat may betransferred Ifrom theheat exchange surface to the boiling refrigerantwithout the entire` amount of the refrigerant tobe boiled coming incontact with said surface and thereby reducing the amount of gaseousfilms or bubbles which would otherwise form onqsaid surface.

A further Objectis to provide an improved method and apparatus wherebythev velocity of the refrigeratlng medium along the heat transfersurface is appreciably increased and thereby anyV Y kaccumulation ofillms or bubbles on said surface is more'effectively removed.

Other objects and advantages of the invention will be hereinafterpointed out or willbe apparnon-volatile constituent.

:senting the heat exchange surface.

ent from a consideration of the accompanying drawing and the followingdescription.

As one important feature of my invention I employ, in addition to thevolatile refrigerant, a second liquid which is substantially non-vola- 5tile at the refrigerating temperature and which is mixed with and flowswith thervolatiie refrigerant along the heat transfer surface. By meansof such liquid a portion of theA vaporization takes place in theresulting mixed liquid and heat is transferred from the heat transfersurface through portions of the liquid and much of the vaporizationtakes place out of direct con tact with the heat transfer surface sothat there Y is reduced liability ofthe bubbles forming on 15 ortraveling along saidsurface. By using a liquid which is a solvent for ormiscible with lubricati ing oil. such oil is diluted or` washed from theheat transfer surface and is prevented from accumulatingon the latter.As a further feature the volatile refrigerant may be delivered in partat least through an injector nozzle which causes a'. rapid flow andcontinued `circulation of the The accompanying drawingA showsdiagrammatically an arrangement of parts jsuitablefor carrying out myimprovedvmethod and constitutingrmy improved apparatus, and it lwill beunderstood thatthe details of construction of. .theyarious parts may bemodified within wide limits as such details, constitute no novel;portion of my invention. In the drawing Figure 1 is a diagrammaticdrawing showing in vertical' section one apparatus which -may beemployed and Figure 2 is a similar Vview showing an `a1 35 ternativearrangement of certain of the parts shown lin Figure 1.` i

My invention may be used in a wide variety of processesand for therefrigerating ofa wide varietyof materials lwhich may be in contact withor circulatedover the separatingwall pre- Merely as an example, I haveshown a unit which may be employed for the freezing of ice cream,chilling of lard, margarine, or otheranaiogous material,v orv fortreatment of other liquids, mixtures, or compounds. Such a unit is shownin the Bottoms and Wood Patent"2,013,il25 andzincludes La *cylinder IIIhaving an agitating. scraping. whipping,

or beating element therein and rotated. by a shaft Il driven from anelectric motor l2 -or any other suitable source of powers. Surroundingthe cylinder is ajacket Il through which the refrigerant liquid iscirculated and inwhich the In Figure 2 an alternative form of unit isillustrated which in most respects is very similar to that shown inFigure l except that it has its axis horizontally' disposed instead ofvertically disposed, and the refrigerant intake pipe I4' enters oppositeto an end wall I9 of the cylinder or other chamber in which the materialis to be treated. As illustrated in both Figures l and 2, therefrigerant jacket I3 is constructed to form a relatively thin annularspace so that the refrigerating medium under pressure will movetherethrough at relatively high velocity. 'This is preferable althoughnot essential and the dimensions of the jacket as well as those of thecylinder Ill and the characterof the agitating means may be variedthrough a comparatively wide scope.

In the system 'illustrated the volatile liquid refrigerant is deliveredunder pressure -through a conduit 25 from the condenser of thecompressor and may flow through a branch conduit past a valve 21 to anaccumulator 28. The valve 21 may be operatively connected toa float inthe accumulator so that a predetermined level of the volatilerefrigerant liquid may be maintained in the accumulator. The conduit 25is provided with a second branch` having a ccntrol valve 29 leading toan injector nozzle 3| acting to withdraw liquid from the bottom of theaccumulator 28 through a pipe 32 leading to the casing 33 around thenozzle and connected to the conduit I4 so that the high pressurerefrigerant fluid escaping from the end of the nozzle 3l will withdrawliquid refrigerant from the accumulator and force it through the pipeI4' into the jacket I3.

The parts so far describedmay be similar to corresponding parts employedin other refrigerating systems.

As one important feature of my invention I use in connection with thevolatile refrigerant a second liquid which is preferably miscible withthe liquefied volatilerefrigerant liquid; substantially non-volatile atthe refrigerating temperature; and a solvent for lubricating oil. I havefound that kerosene is suitablek for4 this purpose, although otherliquids might be employed.

low temperature of the evaporating chamber the'licluidperforms its mainfunction solely' in v'the jacket, the recirculatlng' portionsv of thesystem may be v'so designed that a relatively small amount of suchliquid may be employed.

The liquid should not become viscous at the `b'e continuously circulatedin the refrigerating yfcycle without passing back to the compressor. Asv As illustrated in the drawing. the outlet ll from the jacket I3 leadsto a chamber 35 where the auxiliary liquid together with the unvaporizedportion of the-primary refrigerant may separate. The vapors may passfrom this separating chamber 35 through a conduit 39 which joins aconduit 31 leading from thetop of the accumulator and thence back to thecompressor. This conduit may have a valve 39 beyond the point ofjunction of the conduits 35 and 31 whereby the back pressure in therefrigerating system may be controlled to thereby control the temperaturev in the jacket I3. The separating cham- -ber 35 may have anysuitable form of ballles or any type of eliminator to prevent drops ofliq-v uid from being carried out with the vapors leaving through theconduit 35. The bottom 0f the separating'chamber 35 is connected byaconduit 39 leading to the casing 33 around the injector nozzle 3l.

The system may be supplied withthe proper quantity of the auxiliaryliquid through a supply pipe 4I having a valve 42, and leading to theseparating chamber 35 or to any ...other desired part of the system.

In starting the apparatus the valve 29 may be closed andrefrigerant'liquid will bevdelivered through the conduits 25 and 20tothe accumulator, and such liquid will mix with the auxiliary liquid toforma mixture which will seek its own level in the conduits 32 and 39,the refrigerating chamber,l and the separating chamber 35. Upon openingthe valve 29'the high pressure primary refrigerant will be deliveredthrough the pipe 30 and nozzle 3l, and will induce a flow of primaryrefrigerant through the pipe 32 and the' auxiliary liquid through thepipe 39, and the resulting mixed liquid will ilow into the jacket I3.Some vaporization of the primary refrigerant may take place in theconduit I4 to.chill the liquid before entering the jacket, but the mainevaporation will take place'in the mixed liquid' in thejacket I3, due toabsorption of heat from the heat transfer surface of the cylinder Ill.The unvaporized liquid vtogether with the vapors will pass out throughvthe conduit I5 vand will separate in the chamber 35, the liquidreturning through the conduit 39 for recirculatiomand the vapors goingback to the compressor.

The back pressure on the system, and therefore, the temperaturein thejacket I3, may be controlled manually or otherwise by the valve 38, andmayralso be controlled by a solenoid valve 43 in the conduit 36 andoperated in accordance with the load on the motor. The refrigerating ofthe material to such 'an extent that it is too stiff in the cylinder I0,will result in an addil will cause rthe material to be hardened to alesser extent, thereby relieving the load on the motor and permittingthe valve 43 .to reopen.

' In my improved system the auxiliary liquid I prevents the formation oflubricating oil illms heat transfer surface of the cylinder I9 as 'wellas in the pipes and valves; it permits a' portion of the vaporization totake place in indirect rather than direct relationship to said surface;-it reduces thevolume of the primary refrigerant in respect to thecapacity ofthe jacket I3; and due to its rapid flow, sweeps any bub.bles or gas illms from the heat transfer surface.

in specific gravity of the liquid in the conduits' 32 and 39 andthemixture of liquid and gas in the jacket I3, and this will causeacontinued circulation of the auxiliary liquid upwardly in the jacket I3and into the separator and a returnv of the non-vaporized portionthrough the conduit 3%. The injector insures amorerapid circulation andadds refrigerant to themixed liquid to supplement that supplied throughthe conduit `32 directly from the accumulator. The evaporation which maytake place in the conduit I4 brings the auxiliary liquid Vto a very lowtemperature, so that such liquid by itself acts to abstract heat .fromthe heat transfer surface as well as to conduct heatto portions of theprimary refrigerant not in direct contact with said surface. Uponshutting down the apparatus, all of the primary refrigerantmaybepermitted to evaporate, leaving the auxiliary liquid "in the systemsubstantially free of primary' refrigerant, and thus, when the valve 45is opened the auxiliary liquid may drain through the pipe 46. It may betreated to remove'therefrom the accumulated lubricating oil orother-impurities,

with very little loss of primary. refrigerant. When purified it may bereturned to the system through the inlet 4 I I have referred -tokerosene as the auxiliary liquid, but indicated that other liquids mightbe used instead. For example, a certain percentage of water may beemployed in the system in advdition to the ammonia or whatever volatilerefrigerant liquid may be used, and kerosene. In cases where lubricatingoil does not present any J problem, I may use'water with the ammonia andwithout kerosene.. 'I'he water under the pressures and temperaturesexisting -in the system would not boil, and would serve equally as wellas kerosene for scouring bubbles from the surface of the cylinder I0 andfor conducting heat to portions of the primary refrigerant not directlyyin contact with the heat exchange surface. With 25% or more of ammoniadissolved in water as the auxiliary liquid, there will be no freezing ofthe water content, since such a percentage of aqueous ammonia will lowerthe freezing point of the solution to' a lower temperature thanvisordinarily'required in processes of the character to which I havereferred.

yIt will be understood that the drawing is diagrammatic, and thatinsulation will be employed around all portions of the system wherevheat may be' absorbed from the atmosphere, and

not merely around the jacket I3.

IHaving thus described my invention, what I Vclaim as newand desire tosecure by Letters Patentis: A

l. 'Ihe method of refrigerating a heat transfer.

Y surface which includes injecting a volatile refrigerating liquid intoa stream of kerosene,'cir

culating said kerosene over the surface to be refrigerated, vaporlzingsaid refrigerating liquid `l-:in said stream, and separating the vaporsfrom Y said stream.

2. The method of refrigerating a heat transfer urface which includesinjecting a volatile renon-volatile liquid vfrigerating liquid intoastream of kerosene, circulating said kerosene over the frigerated,vaporizing said refrigerating liquid in sid stream,

surface to be reseparating the vapors' from said l stream after leavingsaid surface. 'and returnhaving a nozzle, means for delivering`relatively from said separating chamber and a volatile refrigeratingliquid from said accumulator to said injector, means for deliveringrefrigerant liquid under premure to said nozzle to effect flow from saidaccumulator and said separator .to said refrigerating chamber, means fordelivering vapor and liquid from said refrigerating chamber to saidseparator, means for delivering separated vapor from said separator, andmeans for returning liquid from said separator to said injector.

' 5. In combination a refrigerating chamber, having an inlet and anoutlet,'a separator having an inlet connected to said outlet and havingseparate gas and liquid outlets, an accumulator, conduits from saidaccumulator and `the liquid outlet of said separator to the inlet ofsaid refrigerating chamber, an injector associated `with said conduits,and means for delivering liquid refrigerant to said injector to effectdelivery of liquid refrigerant from said accumulator and delivery ofrelatively non-volatile liquid from said separator'to said refrigeratingchamber.

6. A refrigerating apparatus including a refrigerating chamber, a sourceofsupply of a volatile refrigerant liquid, a separator spaced from saidrefrigerating chamber, means for `delivering volatile refrigerant liquidfrom said source of supply and relatively non-volatile liquid from saidvseparator to said .refrigerating chamber, means for injecting volatilerefrigerantliquid under high pressure tov enforce said delivery and thecirculation through said refrigerating chamber, and means for deliveringvapors of the refrigerating liquid from said separator.

7. In a refrigeratlns` system, a heat exchange cylinder having a jacket,a separator connected to the upper portion of'said jacket, anaccumulator, a supply line for delivering liquid refrigerant under vlowpressure from said accumulator to the lower portion .of said jacket, asupply line for delivering relatively non-volatile liquid from saidseparator to the lower portion of said jacket, an injector, erant underhigh pressure to said injector to affect rapid'circulation of saidliquids through said jacket, and means for withdrawing vapors from saidseparator. y

8. The method of refrigerating a` heat transmeans for delivering liquidrefrig' fer surface of' an evaporator,` whichv includes 9. The method ofrefrigerating a heat transfer. surface of an evaporator,'whichincludescirculating a relatively non-volatile liquid in a closed cyclehavingsaid evaporator as a part thereof, mixing a volatile refrigeratingliquid with said mst-mentioned liquid in advance 0i' contact with saidsurface, substantially completely separating said` first-mentionedliquid from vapor resulting from vaporizationv of said refrigeratingliquid adjacent to said surface andafter the latter leaves said surface,andjreturni'ng said non-volatile liquid to said evaporator.

10. The method of refrigerating a heat transfer surface, which includescirculating a substantially non-volatile liquid in a closed cycle oversaid surface, then through a separator and back to saidsurface,'accelerating .the ilow of said liquid and refrigerating thelatter by injecting a volatile refrigerant into the-cycle in the direc--tion of flow. and substantially completely separating the vapor of therefrigerant and said liquid in said separator. 1

11. In va refrigerating system, a heat exchange cylinder-.having ajacket, a separator connected to the upper portion of said jacket, anaccumulator,

a supply line for4 delivering liquid refrigerant under low pressure fromsaid accumulator to the lower' portion of said jacket, a supply line fordelivering relatively non-volatile liquid from said separator to thelower portion of said jacket, an injector, means for delivering liquidrefrigerant under high pressure to said injector to affect rapidcirculation of said liquids through said jacket, means for deliveringliquid refrigerant to said accumulator, means for delivering liquid andvapors from the upper end of said jacket to said separator, and meansfor withdrawing vapors from said separator and from said accumulator.

12. The method of refrigerating a heat transfer surface and freeing itfrom illms and bubbles, which includes delivering a mixture of asubstantially non -volatile liquid and a volatile refrigerating liquidat low pressure toan evaporator presenting said surface, flowing themixture rapidly over said surface whereby at least a portion of saidrefrigerating liquid is gasiiled, removing the liquids and gases fromsaid evaporator, separating the gases and liquids, reliquefying thegases and re-mlxing the reliqueiled gases with the substantiallynon-volatile liquid for re-delivery tosaid evaporator.

13. The method of refrigeratinga heat transfer surface. which includescirculating a substantially non-volatile liquid ,under lowpressure in aclosed aasaoco cycle, including an evaporator presenting said surface,and a separator. at spaced points in the cycle, delivering a volatilerefrigerant liquid to the cycle at a point in the'latter where the firstmentioned liquid flows'from the separator to the evaporator, andremoving vapors of the refrigerant liquid from thecycle at theseparator.

14. The methodA of refrigerating a heat transfer surface, which includescirculating a substantially non-volatile liquid under low pressure in aclosed cycle, includingV an evaporator presenting said surface, and aseparator, at spaced points in the cycle, removing vapors of therefrigerant liquid from the cycle at the separator, reliqueiying saidvapors, and returning them to the cycle at a point lnthe latter wherethe first mentioned liquid flows from the separator to the evaporator.

15. 'I'he method of refrigerating a heat transfer n surface, whichincludes circulating a substantially non-volatile liquid under lowpressure in a closed cycle, including an evaporator presenting saidsurface, and a separator, at spaced points in the cycle, removing vaporsoi.'l the refrigerant liquid from the cycle at the separator,reliquefying said vapors, and returning a portion thereof at lowpressure to the cycle at a point in -the latter where the firstmentioned liquid flows from the separator -to the evaporator, andreturning another portion thereof at high pressure and injecting it intothe cycle to increase the speed of flow in the cycle.

16. The method of refrigerating a heat transfer surface and removingfilms and bubbles there` from, which includes entraining 'a relativelynonvolatile liquid in a high velocity streamof yvolatile refrigerant,effecting vaporization of the volatile refrigerant to producerefrigeration, utilizing .the action of said high velocity stream toproduce a rapid flow of said non-volatile liquid over said surface in amanner to scour films and bubbles from the surface, substantiallycompletely removing vapors 'from .said non-volatile liquid and restream.

17. 'Ihe method of refrigerating a heat transfer surface andremoving'nlms and bubbles therefrom, which includes providing a mixtureof a volatile refrigerant and a relatively non-volatile liquid in whichsaid refrigerant vaporizes .to effect refrigerating action, producingrelatively high velocity flow of said mixture over said surface in amanner to cool the surface and to remove films and bubbles fromthe'surface by the scrubbing action of said liquid, separating thevapors from the liquidand returning the liquid for recirculationoversaid surface.

v BRUCE DE HAVEN MILLER.

turning the liquid' for r'eentralnment in saidI

